The [3.3.1]-bicyclic amine, exo -8-benzyloxymethyl-3-ethoxycarbonyl-4-hydroxy-1-azabicyclo[3.3.1]non-3-ene ( 1 ), has been shown to be a potent competitive antagonist against the hM 1 –hM 5 muscarinic receptors. This heterocyclic system has not been extensively evaluated despite the notable activities reported for other bicyclic amines. Synthetic strategies permitted the selective alteration of five structural sites in 1 . Pharmacological evaluation demonstrated that modification of either the C(3) alkoxycarbonyl or the C(4) enol units in 1 gave compounds with high affinity for the hM 1 –hM 5 muscarinic receptors with selectivity for the hM 2 receptor.
